Pyrex

Question

I worked as a Mashgiach for many years for the Va'ad Ha'Rabannim in Washington, DC. Their official policy is that Pyrex is a different type of glass, made with different types of elements, and therefore is porous. My father, an Orthodox Sephardic rabbi says that Pyrex is non-porous, and therefore does not need to be seperated between dairy and meat. Please clarify the Sephardic position on the matter, as well as the reasoning for both positions. Thank you very much.